[AppStream] Additional markup support in descriptions

[Richard Hughes]

On Sun, 28 Jul 2019 at 07:47, Robert Ancell <robert.ancell at canonical.com> wrote:
> I guess that would mean supporting both <code> and <pre>.

I think various things would break trying to support <pre> -- a lot of
current and legacy tools that import and export AppStream assume that
XML whitespace isn't important. My vote would be to add <code>, <em>
and <strong> and leave it at that.

Richard